code: def prepare_folder_for_valid(
      net_str, net_config, run_config, exp_dir
  ):
      os.makedirs(exp_dir, exist_ok=True)
      monitor = ExpdirMonitor(exp_dir)
      json.dump(
          net_config.get_config(),
          open(monitor.net_config_path, "w"),
          indent=4,
      )
      json.dump(
          run_config.get_config(),
          open(monitor.run_config_path, "w"),
          indent=4,
      )
      pickle.dump(net_config.renew_init(None), open(monitor.init, "wb"))
      json.dump(
          {"net_str": net_str},
          open(os.path.join(monitor.expdir, "net.str"), "w"),
          indent=4,
      )
  
imports: import os
  import subprocess
  import json
  import pickle
  import numpy
  from ..data_providers.utils import get_data_provider_by_name
  from .expdir_monitor import ExpdirMonitor
  from ..expdir_monitor import distributed
label_desc: Use image node_id 7 for calling the ArchManager obj's underlying member method code with example usage: obj.prepare_folder_for_valid(net_str, net_config, run_config, exp_dir) without return types